Local correlations in the 1D Bose gas from a scaling limit of the XXZ chain

TL;DR

This paper derives a general multiple integral formula for local K-body correlations in the 1D Bose gas, applicable to various states, and explicitly factorizes it for K<=4, including new results for K=4.

Contribution

It introduces a novel integral formula for local correlations in the 1D Bose gas and explicitly factorizes it for K up to 4, extending previous results.

Findings

Explicit factorization for K<=4 correlations

New formula for K=4 correlations

Numerical validation of the formulas

Abstract

We consider the K-body local correlations in the (repulsive) 1D Bose gas for general K, both at finite size and in the thermodynamic limit. Concerning the latter we develop a multiple integral formula which applies for arbitrary states of the system with a smooth distribution of Bethe roots, including the ground state and finite temperature Gibbs-states. In the cases K<=4 we perform the explicit factorization of the multiple integral. In the case of K=3 we obtain the recent result of Kormos et.al., whereas our formula for K=4 is new. Numerical results are presented as well.